Deodorizing dispensers (also referred to as air fresheners) can essentially be divided into four categories: those with natural convection of the active substance (air-freshening material); those with mechanically-assisted circulation; those with thermally intensified evaporation of the volatile components of the substance; and room-spray dispensers which spread a fine cloud of droplets by means of a pump operated in bursts (EP-A1-0 127 573 and WO 94/04280).
These latter dispensers intermittently spray an intense cloud of fragrance, but in small rooms. on account of being mounted on or near a door, have the tendency to spray the person entering or leaving the room.
In contrast, another device (WO 80/00792) uses a continuously operated, battery-powered fan which blasts the surface of a liquid active substance and steadily evaporates it. This requires the aerated liquid surface to be at a constant level, which is achieved by means of a liquid supply arranged in the manner of a bird bath, i.e. via a bottle with its mouth immersed in the liquid.
The disadvantage of this device is the constant consumption of active substance, in particular when used in washrooms and/or toilets which are only in intermittent use. In toilets in office buildings, for example. this can also lead to "overperfuming" during the relatively great periods of non-use and, furthermore, requires excessively frequent and uneconomical replacement of the refill bottles containing the active substance. Battery consumption is high; the service intervals needed are therefor very short and may be in the range of a few days.
Hygiene problems also arise; on account of the continuously operating fan, there is a large and continuous supply of germs and the like to the open liquid surface. Viable encrustments in the open containers form.
U.S. Pat. No. 4,078,891 describes an air cleaner connected to a power supply system. The air to be cleaned is drawn in by suction by means of a fan, passes over a filter and is enriched in an inner part of the housing with an active substance and is then discharged. The enrichment occurs over wicks immersed in bottles and/or evaporation tablets on a grid. Underneath the grid is located a relatively large mains operated fan as well as an accompanying electronic controller, which switches the fan sequentially on and off in a predetermined manner.
The disadvantage of this device is the absence of a possibility or requirement-dependent control of function, because the inherently low rate of evaporation allows only short standstill times and therefore makes a mains connection necessary, thus forming a security risk in wet areas such as toilets etc. and calls for special costly installations. Further, outside air streams over the filter through the inner part of the housing and the delivery pipe, even when the fan is switched off, so that the active substance contained therein continuously degrades in an uncontrolled manner.
Therefore, the object of the present invention is to provide a hygienic device which produces an effect precisely adapted to the requirements of the users, which avoids spraying people and, furthermore, is economical to operate and easy to maintain.
In addition, the device should be as versatile as possible and be suitable in particular for toilets, urinals and washrooms. The noise generated by the device should be minimal so that it may also be used in other areas without problem, for example in waiting rooms, lifts, telephone booths, etc.